{"id":"CVE-2026-59928","aliases":["PYSEC-2026-2216","GHSA-ffq3-xpv3-j92q"],"title":"Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a Markdown document containing many repeated or distinct …","summary":"Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a Markdown document containing many repeated or distinct reference-link definitions causes quadratic work in src/mistune/block_parser.py and the ref_links en…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","vendor":"mistune","product":"mistune","ecosystem":"pip","affected":["mistune < 3.3.0"],"patched":["mistune 3.3.0"],"published":"2026-07-08","updated":"2026-07-13","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/PYSEC-2026-2216","references":[{"url":"https://github.com/lepture/mistune/releases/tag/v3.3.0"},{"url":"https://github.com/lepture/mistune/commit/2b04d7ba341c16ac78fe82d3076bdd5c3de87c69"},{"url":"https://github.com/lepture/mistune/security/advisories/GHSA-ffq3-xpv3-j92q"}],"tags":["osv","pip"],"epss":0.00651,"epssPercentile":0.49779,"ingestedAt":"2026-07-13T18:58:08.219Z","slug":"CVE-2026-59928","body":"## Overview\n\nMistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a Markdown document containing many repeated or distinct reference-link definitions causes quadratic work in src/mistune/block_parser.py and the ref_links environment dictionary handling, allowing denial of service through CPU exhaustion. This issue is fixed in version 3.3.0.\n\n## Affected packages\n\n- `mistune < 3.3.0`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `mistune 3.3.0`","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}